First Report of Colletotrichum siamense Causing Leaf Spot on Machilus pauhoi in China

作者：Baishuan Lv, Yong Cheng, Lijuan Zhang, Rou Ye, Ying Qin, Yang Zhang · 发表于：Plant Disease · 年份：2022 · DOI：10.1094/pdis-08-22-2005-pdn · 被引用次数：2 · 研究领域：Plant Pathogens and Fungal Diseases、Mycorrhizal Fungi and Plant Interactions、Plant-Microbe Interactions and Immunity

Machilus pauhoi Kaneh. is an excellent evergreen broad-leaved tree species widely grown in China for its ornamental and economic value (He et al. 2022). In September 2021, a leaf spot was observed on M. pauhoi plants on Guantian forest farm (27°06'15.6″N, 114°34'20.72″E) in ji' an city, Jiangxi province, China. The disease incidence was estimated to be above 20%. The symptoms began as brown irregular spots, then the spots gradually expand over time, with a gray-to-brown center and dark brown-to-black edges. Small infected tissues (3 to 5 mm2) were surface-sterilized in 70% ethanol for 30 s and 2% NaClO for 60 s, and rinsed three times with sterile water (Ju et al. 2021). Tissues were placed on potato dextrose agar (PDA) and incubated at 25°C. Pure cultures were obtained by transferring hyphal tips to new PDA plates. Twenty-two isolates of Colletotrichum ssp. were obtained (isolation frequency about 78%). Three representative single-spore isolates (PN-1, PN-4, and PN-9) were used for morphological studies and phylogenetic analyses. Colonies on the PDA of the three isolates were white to gray with cottony mycelia and grayish-white on the undersides of the culture. Conidia were single-celled, straight, hyaline, cylindrical, clavate, and measured 11.4-16.8 ×4.1-5.5 µm (13.2 ± 1.0 × 4.4 ± 0.3 µm, n = 100). Appressoria were brown to dark brown, ovoid to clavate, slightly irregular to irregular, and ranged from 5.2-8.8 × 4.1-6.2 µm (6.7 ± 0.2 × 5.1 ± 0.3 µm, n=100). Morphological fe...